lol leave all your important possessions at home and only take what you need like clothes and stuff cause those are always replaceable. As for me the only expensive thing I would take would be a camera to take pictures with.

Well, if I were in my room when I realized what was happening, I'd grab what I can and go. Not a whole bag, but just what I can carry in my arms.
Some things, whether old or new, have an amount of sentimental value :/

Now one of my friends would probably fit the bill of grabbing every last possession before leaving the ship. We were staying at a hotel and she suddenly woke up smelling smoke. She bolted out of bed and started grabbing all her stuff before any of us even smelled it.

Since you would have to wait around in the freezing waters of the North Atlantic for about four hours until being rescued (following the time-line of the Titanic), it would probably be a good idea to bring some warm clothes along.